Intercommunicating telephone and signal system



April 28, 1931. s sTY ET AL INTERCOMMUNICATING TELEPHONE AND SIGNAL SYSTEM Filed Oct. 24, 1929 2 Sheets-Sheet 1 INVENTORS THEODORE SISTY Ana R035 L. PEA/NE,

BY FM AMuA,

ATTORNEY April 28, 1931. 5|$TY ET AL 1,802,675

INTERCOMMUNICATING TELEPHONE AND SIGNAL SYSTEM Filed Oct. 24, 1929 2 Sheets-Sheet 2 INVENTORS THIQDDIE Sun Aufl RQGEHT PEA/ME) BY 8% MA ATTORNEY Patented Apr. 28, 1931 UNEE STATES THEODORE SISTY AND ROBERT L. PENN EY, OF ASTORIA, NEW YORK INTEROOMIEUNIOATING TELEPHONE AND SIGNAL SYSTEM Application filed October 24, 1929. Serial No. 402,035.

This invention relates to improvements in an inter-communicating telephone and signal system of a type known as the selective ringing-selective talking system.

The invention has for its object to provide a selective ringing-selective talking intercommunicating telephone and signal system With the additional feature that each and all conversations enjoy, absolute privacy; that is to say, when any two or more stations are in conversation no other station or stations (not desired) may cut in on or interfere with any of the said stations in conversation.

According to the present invention there may be as many conversations carried on as there are pairs of instruments in the system, enabling every station to be in use at the same time. For example, on a twenty station system there may be ten simultaneous conversations, each separate and private. Whereas normally each conversation is strictly private, three or more stations may be connected for conference or other uses, merely by throwing the desired stations keys at one keyboard. 7 i g The invention is more fully described in the following specification, set forth in the appended claims, and illustratively exemplified in the accompanying drawings, in which Figure l is a wiring diagram of an inter-communicating system embodying four stations, Figure 2 is a wiring diagram ofa larger installation showing individual station batteries which are centrally located and with battery leads brought to each station; and Figure 3 is a diagram of a system embodying a common battery used in connection with a retardation or impedance coil, which is inserted, in series, in each battery lead at every station, and afixed condenser of high capacity connected across the two coilsat each station.

Referring to the drawings and particularly to Figure 1, 1, 2, 3 and 4 denote the four stations of the improved system. Each station comprises a telephone receiver R and a transmitter T. In the lines from the receiver R and transmitter T is a hook or cradle switch A, A preferably of the jack spring leaf type, operated by lifting the receiver off the hook or cradle of the instrument. In normal position with phone on stand, there are two breaks and one make, while in operated position,with phone off the stand, there are two makes and one break, the latter break opens the buzzer circuit, contacts 1 and 2 being the actuating springs. The buzzer B is connected to the battery X at its negative pole, the positive pole being in the line with the spring contact 1. The spring contact 2 is in the line running to the negative pole of the battery X. A low resistance relay Z, with single contact, normally open, is in the auxiliary signalling line of the station, the

contact being made when the current is passed through winding and closing buzzer circuit. Each station is provided with visual signals in the form of low voltage lamps L, one for each outside station. The lamps L are connected by individual double-locking single pole, double-throw switches S, which may be of the cam, toggle or button type, operated by hand from the outside of the instrument. In normal position the lamp contact is made and outgoing contact is broken,

while in operated position the lamp 'L is off and calling contact is made.

The system of inter-office communication. herein operates substantially as follows: JVhen a key S at one station is thrown to call an idle station, the buzzer B at the called station is audible in the calling stations receiver. This acts automatically as a busy signal, in that, if the station called were busy, no buzz would be heard in the receiver R of the calling station. The buzzing is continuous when a key S is thrown to call another station; thus, with a single operation, the calling station is connected to the desired station and the buzzer B is operated simultaneously, eliminating thenecessity of holding down the key S or of pressing a separate ringing button until answered. p

The particularly important feature of the present circuit is that while all conversations are absolutely private, either one or both of any two stations in conversation may receive a visual signal through the lamp L of any other station or stations trying to call. When a phone is lifted off of its stand to answer a call, hidden switch 3 automatically disconnects the buzzer B, but does not affect the lamp circuit. The lamps L remain lighted until their respective keys S are thrown to answer. In this manner he stations in con versation may receive a visual but not an audible signal from any other station or stations. It follows, of course, that there is no interference with the conversation as would be the case if an audible signal were received while the conversation were going on. This feature is especially desirable in the case wher e for instance, two minor employees were holding a conversation and the lamp L of an important erecutives office glowed on one of their boards, it would be a signal to disconue the cot versation and immediately answer the pr leged'ei iecutives call.

Local battery X isshown at each station, which is the preferred method on small systems for the reasons that each station, having its 0 n source ofcurrent supply, there is no efi ect on the other stations, or the system as a whole, if their batteries fail; and further that there is no line drop between battery source and remotely disposed stations as would be the case with the batteries centrally located; and still further, that there is no possibility of inductive or other cross talk which mightoccur if battery conductors were runin the connecting cable or if a common battery with retardation coils and condensers were used.

On larger installations (a greater number of stations) individual station batteries X may be centrally located and battery leads :1? brought to each station, as illustrated in Figure 2. I

In connection with still larger systems, a common battery X is used with a retardation or impedance coil Y, the latter being arran ed in series in each battery lead at every station and'a'condenser WV is connected across the coils Y, as illustratively exemplified in Figure 3. lVhen a common battery is used for operating the phones, an additional battery common to'all stations is used for signal ing. However, regardless of the kind or manner of making the connections to the bat teries or other source of current, the basic circuit remains unchanged.

All contacts are shown in the normal or unoperated positions, contacts 1 and? being the actuating spring contacts of the hook switch. Contact 1 is normally closed to complete the buzzer circuit. lVhen switch A A is operated by removing the phone from its book, contact member 1 opens the buzzer circuit and coupled with contact member 2 closes the talking circuit.

The relay Z when energized by the incoming call and by the calling stations battery, operates its armature and contact so as to 'close the buzzer circuit. The incoming cur rent, that is, the plus side of the calling stations battery, after passing through the calling stations receiver continues on through the relay winding, and to that stations lamp, thereby lighting it, after which it passes through the lamp contacts and the calling stations outgoing contacts back to the source of battery. The relays and lamps L and transmitter are operated by the calling stations battery X, the buzzer B, and receiver It being operated by the stations own battery. i

Having now described our invention, what we claim and desire to secure by Letters Patent is:

1. In an inter-communicating telephone system, a plurality of stations, each thereof being provided with a phonea-nd a circuit therefor including a battery, a normally open buzzer circuit in connection with the phone circuit and battery and an inter-station circuitto establish communication from one sta tion phone to another, each station having a relay in the inter-station circuit to close the buzzer circuit, an individual lamp to provide a visual signal from every other station, and an individual circuit closer for every other station normally operating to allow the flow of current from the other station to pass through the called station circuit to give a visual signal, close thebuzzer and connect the phone of the calling station with that of the called station, and means for breaking the buzzer circuit when the phone is in use.

2. In an inter-communicating telephone system, a plurality of stations, each thereof being provided with a phone and a circuit therefor including abattery, a normally open buzzer circuit in'connection with the phone circuit, a normally closed switch in the buzzer circuit opened when the phone is in use, a normally open switch in'said buzzer circuit, an inter-station c1rcu1t to establish communication between stations, a relay at each station in the inter-station circuit to effect the'closing of the normally open switch-in the buzzer circuit, a plurality of lamps at each station, one lamp foreach other station and in the circuit with the relay, a double switch foreach lamp and a connection with the correspond ing lamp of another station, said switches being normally closed to the lamps of their station and open'to the lamps of the other stations, whereby closing ofa switch will open the circuit of the called stations lamp in the calling station and close the circuit between the'phones of the two stations, and energize the relay to close the switch and buzzer circuit which remains operative until the phone of the called station is brought into use.

3. In an inter-communicating telephone"- system, a called station and a calling station, each thereof having a phone circuit, a normally open buzzer circuit in the phone circuit, a connection in the buzzer circuit to further break the latter circuit when the phone is brought into use, a normally open switch in the buzzer circuit and an inter-station circuit between said phone circuits comprising a relay to effect the closing of the switch in the buzzer circuit, a lamp, and a double acting switch normally closed in the inter-station circuit between the calling station lamp of the called station and capable of being operated to signal the called station, whereby the circuit between the stations is closed to connect the phones, energize the relay to close the buzzer circuit and light the lamp in the called station, the buzzer circuit being broken by bringing the called station phone into use. In testimony whereof they have affixed their signatures.

THEODORE SISTY. ROBERT L. PEN NEY. 

